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Weather Fronts
• Front: the boundary that
separates two different air
masses.
• There are four types of fronts.
– Warm Fronts
– Cold Fronts
– Stationary Fronts
– Occluded Fronts
Warm Fronts
• Forms when warm air moves into
an area formerly covered by
cooler air
• Warm air gradually rises over the
cold air  light showers that
come before the warm air
Warm Fronts
• Produce light-to-moderate
precipitation
• Winds will shift from the east to the
southwest
• Shown as a red line with semicircles
that point towards the cooler air
Cold Fronts
• Forms when cold, dense air
moves into a region occupied by
warmer air
• Cold air moves quickly into the
area of warmer weather 
pushing the warmer air above
the cold air.
Cold Fronts
Force of lifting the warmer air above
the cold air can produce
thunderstorms
• After the storms the weather is cold
• Shown as a blue line with triangles
that points towards the warmer air.
Stationary Fronts
• Stationary Front – a cold front
and a warm front move
parallel and in the same
direction together
–Neither the cold air mass or
the warm air mass move
towards each other.
Stationary Fronts
• Gentle to moderate precipitation
can fall along the stationary front.
• Shown by blue triangles on one
side of the line and red
semicircles on the other side of
the line.
Occluded Fronts
•
• An active cold front takes over a warm
front an occluded front forms
• The cold front moves in where there is
a warm front with a nonmoving cool
front on the other side
Occluded Fronts
• The cold front and cool front
squeeze the warm front upward,
causing heavy, then light rain.
• The occluded front will twist and
turn around the warm front.
•
Middle-Latitude Cyclones
• Middle-latitude cyclones are
extremely low pressure systems 
heavy storms.
• The warm front is pushed upward
as the cold front moves in 
occluded front
• Occluded front grows 
precipitation increases, pressure
drops, and wind increases
– Storms take one or two days to
completely displaced the warm air.
• Air higher up in the atmosphere
fuels the energy for the middlelatitude cyclones
– Hot air spreads out aloft and pulls
more air upward from below 
middle-latitude cyclone
Assignment
• Atmosphere Study Guide